Renovation of flat roofs typically involves repairing or replacing the existing roof to improve its performance and extend its lifespan. The renovation process may include a range of tasks depending on the condition of the roof, such as repairing leaks, replacing damaged or deteriorated materials, adding insulation, or upgrading drainage systems. This research aim was to establish the priority of renovation of flat roofs of the public building based on the principles of multi-criteria analysis and fuzzy set theory, using the multi-criteria method PROMETHEE II in fuzzy logic form (F-PROMETHEE II). The proposed approach is adequate due to its ability to transform the uncertain and vague information received from an expert into a fuzzy number. This way, the objective outcome can be obtained, the criteria conflict removed and the alternatives ranking and mutual comparison enabled. It was necessary to analyze the existing literature, the flat roofs of a public building in terms of their current condition, and define the main goals and criteria for the roof renovation project. Based on the defined goals and criteria, the roofs are evaluated and ranked according to the priority for renovation. The planning process of renovation of flat roofs was carried out specifically on the building of the Faculty of Civil Engineering, Architecture and Geodesy in Split.